A friend of mine who designs aviation hydraulic pumps tells me that some of the hydraulic systems on the 747 use the fuel tanks as a heat sink for the hydraulic oil. Heat is imparted to the hydraulic fluid as it is compressed during the act of being pumped and the fluid is routed to heat exchangers in the fuel tanks where the heat is then transferred to the jet fuel. His speculation is that Flight 800 experienced a runaway hydraulic pump (flight crew couldn't get it off line) and the hydraulic fluid got exceedingly hot which in turn heated the fuel in the center tank to it's flash point.
I don't know if this would be possible however I do know that deadheading a pump will cause whatever fluid is being pumped to get REALLY hot in a short period of time.
Listening to the story change as it went from local radio to national news was amazing. From initial reports of people seeing a streak of light from the ground, then an explosion, then hearing the explosion, the news shifted to people who claimed they heard the explosion, then turned and saw it. Silly idiots forgot that light travels faster than sound.
Then all the ridiculous news stories such as "No SAM could hit a jetliner," to be contradicted by military callers giving the specs of SAMs that could, etc.
Good theory except for one minor point. The center fuel tank on Flight 800 was empty on takeoff.